Jack hammer bit



May 12, 1936- N. BRENHOLM JACK HAMMER BIT Filed April 15, 1935 Inventm- A els Bren/201m flmaarih Attorney Patented May 12 1936 UNITED STATES PATENT OFFICE JAoK' HAMMER nrr Application April 15,

1 Claim.

This invention relates to drill bits and more particularly to bits especially designed for operation by a jack hammer.

An object of the present invention is to provide a bit of this character characterized by such a construction that in operation, the bit at all times will be kept clear and free from cuttings and, consequently, will not choke or stick.

Briefly, the invention consists in the provision of a jack drill bit provided with multiple wings or blades with cutting edges which are spiral in form making the blades tapered and slanting, and also having an air passage therethrough and opening outwardly in such relation to the blade to insure such a cooperation with the blades that the cuttings "or particles are easily reduced to dust and expelled from the hole by the force of air or water passing from the passage in the bit.

The invention together with its objects and advantages will be best understood from a study of the following description taken in connection with the accompanying drawing wherein:

Figure 1 is a view mostly in elevation of the bit, and with parts broken away and shown in section.

Figure 2 is a bottom plan view of the bit. Referring to the drawing by reference numerals it will be seen that the bit indicated generally by the reference numeral 4 has a somewhat tapered head portion 5 merging into a somewhat flared body portion, the head portion 5 being provided with a shank 8 having-a threaded socket 6, the latter forming no part of the present invention. Further in accordance with the present invention the drill 4 is provided with multiple wings or blades 8 which are spiral in form making the blades tapered and slanting, as shown. As illustrated the blades 9 have a spiral twist clockwise from the top of the bit, which, as will be clear to those skilled in the art, ls counter to the direc innerendsotthepointsilotthebitandasbest the bottom of the bit and are beveled. At thO 1935, Serial No. 16,524 R S S U ED AUG 1 7 193'! shown in Figure 2 the bottom of the bit is provided with a central depression l2 serving as a guide hole of indentation in the center of the bottom of the bit.

Also, axially through the center of the bit is a passage II which slightly upwardly from the bottom of the bit extends laterally and at a downwardly incline as at llato open through the trailing or following face of one of the blades 9 to the end that the air or water through the passage will discharge through the end I la thereof in such a manner to cooperate with the blades for insuring the expelling of the dust-ground cuttings from the hole by the force of air or water, as the case may be, issuing from the outlet end lid of the passage.

The object of the spiral blades, and in having the spiral twist clockwise from the top to the bottom of the bit is that, the drill operating in a cbunterclockwise direction, any particles of rock or mulk having a tendency to gather above the cutting edges III are worked back under the cutters by passing down the grooves with the result that the particles or cuttings will be ground practically to dust thereby preventing choking or sticking of the drill. t

It will be apparent that a bit of this character will tend to efficiently force particles of the rock or cuttings downward to be crushed and pulverized by the action of the points or edges ill of the blades and in such a crushed pulverized state to be expelled from the hole by the force of the water or air issuing from the passage ll, and as such a spiral arrangement of the grooves and blades will insure, as above pointed out, against the choking and sticking of the bit while in operation.

Having thus described the invention, what is claimed as new is:

A bit for use with jack hammer drills adapted to be rotated normally in a counterclockwise direction, said bit having a multiplicity of integral spiralblades twisting clockwise from the top to the bottom of thebit and providing in alternation with the blades grooves having a spiral twist corresponding to the spiral twist of the blades, said bit also including an integral shank and a passage extending longitudinally of the shank and the bit and opening laterally through one of the trailing faces of one of said. blades, and said blades having cutting edges disposed slightly lower than the central part of the lower surface 01 the bit, said cutting edges being beveled.

ms sannnom. 

